Wire tensioning tool



May 2, 1961 l.. J. slMs WIRE TENsIoNING Toor.

2 Sheets-Sheet 1 Filed NOV. l5, 1954 May 2, 1961 L. J. slMs 2,982,520 WIRE TENsIoNrNG Toor.

Filed Nov, l5, 1954 2 Sheets-Sheet 2 Leedfe James S MS :NVENTQ (Q 2,982,520 WIRE TENSIONING TOOL L'eslie James Sims,

& vPartners P2113/ Cardiff, Wales, assigner to Ecrofnier Limited, Cardiff, Wales, a British com- Filed Nov. 15, 1954, Ser. No. 468,918 Claims priority, application Great Britain Nov. 17, 1953 7 Claims. (Cl. 25429) This invention relates to hand tools and has for its chief object to provide a simple tool by means of which a-wire or the like may be stressed up to, and not beyond, a predetermined limit, and from which the wire or the like may he quickly and easily released when required,

the tool thus being particularly applicable to the tension-V ing of wires in the production of pre-stressed concrete.

`The hand tool according to the present invention cornprises a cylinder slidably arranged within a barrel and adapted to be moved axially therein by means of a spur wheel carried by the barrel engaging with a rack on the cylinder, said cylinder being provided with an axial bore through which the wire or the like may pass and, at its forward end, with a two-part one-way grip device normally adapted to permit free movement of the wire or the like into the bore, but to prevent movement of the wire orf-the ,like out of the bore, and a projection at the forward end of one part of the said one-way grip device adapted to be engaged by a stop at the forward end of the barrel when the barrel is moved rearwardly of the cylinder to cause release of the one-way grip device.

The spur wheel is adapted to be driven from a projecting shank through a ratchet and pawl device and, in use, said shank is engaged by a torque wrench which will ensure that the Wire can be tensioned up to, but not beyond, a predetermined limit.

Preferably, means are provided for causing forward movement of the cylinder in the barrel when the said barrel is moved rearwardly to effect relative movement between the two parts of the one-way grip device to facilitate release of the wire or the like as will be explained more fully hereinafter. f

`In order that this invention may be the more clearly understood and readily carried into effect, reference may belmade to the accompanying drawings, which illustrate by way of example certain convenient embodiments of this invention, and in which: -Figure 1 is a longitudinal section through the hand tool according to the present invention, and Figure 2 is a section on line 2-2 thereof. Figure 3 is a somewhat diagrammatic view illustrating the manner in which the hand tool laccording to the present invention is used for pre-stressing wires, and

, Figures 4, 5, 6 and 7 are again somewhat diagrammatic views illustrating the parts of the device in the various positions they assume during the carrying out of .the

various operations of stressing the wires.

2 Figure 8 is a longitudinal section through an adaptor for use' with the hand tool according to the present inventionyand Figure 9 is a view showing the manner in which the said adaptor is used.

. Referring now to the accompanying drawings, the tool o'rifhand jack therein illustrated, Vwhich is intended more' particularly for tensioning wires in the productiony of pre-stressed concrete, comprises an outer barrel 10 within which is slidably arranged, on suitable bearings if desu-ed,

2,982,520 Fente? Mey. 2. l??

ward end of the barrel is closed by a stop 14 having an central conical lead-in hole 15 to receive the wire 13v and a like stop 16 may also be provided at the rear end of the barrel, the conical hole 17 therein facing forwardly` to facilitate threading of the wire through the tool. 'The cylinder 11 may also be provided at its forward end with a conical mouth 18 for a like purpose. y

At the forward end the cylinder 11 is provided with a two-part spring-operated one-way tensioning grip A, pref` erably of the form described in French Patent No. 1,118,078, and comprising an outer barrel 19 with a tapered bore 20 and an inner cylinder 21 carrying a plurality of balls or the like 22 co-operating with the said tapered bore 20. lThe cylinder 21 of the one-way grip device is provided with a cap 23 which projects forwardly towards the front stop 14 of the barrel 10 andfagain is provided with a conical lead-in hole 24 to facilitate threading of the wire. v

The cylinder 11 is formed on its underside as a longitudinal rack 25 which is engaged by a spur wheel 26 adapted to be driven through a ratchet and pawl illustrated diagrammatically at 27 from a shaft 28 having a` projecting shank 29. In use, as will be described hereinafter, the shank 29 is engaged by a suitable known form of torque wrench (Figure 3).

T'he tool or hand jack accordng to the present invention is used (Figure 3) with a second one-way grip devicev B which is tixedlypositioned and functions as a holding one-way grip device, and is preferably of the form described in French Patent No. 1,118,078, and in adapted to function in the same direction as the tensioning oneway grip device A in the hand jack. To tension a wire, the wire 13 is anchored or gripped at its free end in what is hereinafter referred to as the end grip C and is passed through the holding one-way grip device B at the other end of the mould. The wire 13 is then threaded tension which it is desired to have applied to the wire,

is engaged with the shank 29 of the spur wheel 26. The torque wrench 31 is now rocked backwards and forwards. As the torque wrench is rocked backwardly (Figure 4) Vto move the cylinder 11 rearwardly in the barrel 10 the wire 13 will be gripped by the tensioning one-way grip device A in the hand jack and will be pulled rearwardly thereby tensioning the same. When the torque wrench is moved forwardly (Figure 5) the tensioning one-way grip device A in the hand jack tends to move back to its original position, but the wire wlil be gripped in the holding one-way grip device B thus avoiding loss of tension. The wire is thus tensioned by steps' with `thegrip thereon alternating between the tensioning one-way grip device in the hand jack A and the holding one-way' grip device B. The torque wrench 31 is rocked back-4v wardly and forwardly until the desired tension has heenf applied to the wire 13, whereupon the torque wrench will slip or register the tension applied and we shall b ej left with a wire at a predetermined tension grippedati one end in the end grip C and at the otherrendinth' second tensioning one-way grip device B without apprecf-l able loss of the tension applied thereto by operation lof t torque wrench 31.

When it is desired to release the wire the barrel of the hand jack is pulled outbaekwardly away from the abutment 30 so as to bring the stop at the forward end of the hand jack into engagement with the projection 23 on the cylinder of the one-way grip device. By this means the spring 34 of the tensioning one-way grip device A will be compressed and the grip on the wire 13 in the hand jack will be released. As the wire is gripped by the holding one-way grip device B no loss of tension will OCCUI.

Now it will be appreciated that the balls or the like 2,2 of the tensioning one-way grip device A will bite into the wire 13 when gripping the same and will raise burrs over which the balls or the like have to ride before the wire can be freed from the hand jack. In order, therefore, to facilitate the release of the wire 13 from the hand jack it is preferred to provide means for moving the cylinder 11 forwardly in the barrel 10 whilst the projection 23 on the cylinder 21 of the one-way grip device A is engaged by the front stop 14 of the barrel 10. This will cause relative movement between the cylinder 21 and barrel 10 of the one-way grip device A, and will free the balls much more quickly to enable them to ride over any burrs that may be present (see Figure 7). This move ment is conveniently effected by engaging a tommy-bar 3S in the spur wheel spindle (shown diagrammatically in Fig. 3) so that the cylinder 11 may be pushed forwardly in the barrel 1G. No slot or entry in the spur Wheel spindle is illustrated in Figs. l and 2 because the showing of the tommy-bar 35 in Fig. 3 is intended to be illustrative only and not to be precise showing of a Working embodiment thereof. In practice, the spindle 2S can be extended on the side opposite to the shank 29, and a hole may be drilled in this extension into which the tommy-bar can be inserted. Alternatively, on the opposite end of the spindle to the shank 29, a slot can be cut into which a special tommy-bar can be inserted. Such an arrangement also has the advantage that it facilitates the threading of the wire 13 through the hand jack as it can be used to nullify the action of the compression spring 34 in the one-way grip device A, thereby freeing the balls from the radial bias which would otherwise be applied to them by the compression spring 34.

An indicator may be provided in or on the barrel to indicate the movement of the cylinder within the barrel and hence the amount by which the wire has been stretched.

Since the one-way grip device is detachably mounted, for example by being screwed on the forward end of the cylinder 11 as shown at 36, it will be appreciated that the hand jack may easily be adapted to operate on different sizes of wire by replacing the original one-way grip device A by a further device adapted to take a different range of sizes of wire.

If desired, and as shown in Figures 8 and 9, an adaptor may be provided to enable the hand jack according to the present invention to be used with the standard wedge grips D which are provided on the existing anchor blocks E, thereby avoiding the need to provide a second one-Way grip device B. Such an adaptor may comprise atube 40 which, at its rear end, is adapted to be engaged with the forward end of the hand jack and, at its forward end 42, to fit about the wedge grip D in the anchor block E. A plunger 43 is slidably arranged within said cylinder 40 and is urged forwardly by a compression spring. The plunger 43 carries a tubular rod 45 which preferably, when the adaptor is not in use, projects slightly beyond the forward end of the cylinder 40 (Figure 8). In use, the wire 13 is threaded through the wedge grip D in the anchor block E, through the adaptor and through the hand jack as before. The forward end of the adaptor which is, of course, mounted on the hand jack, is now located about the wedge grip casing D and pressed up against the same, the inside of the cylinder 40 or a lining 46 therein being provided with a shoulder 47 to form an pressure exerted on the wedges by the plunger rod 45.

The hand jack according to the present invention is simp'e and cheap to produce and can easily and quickly be operated by a single operator to tension the wires up to a predetermined limit and quickly to release the same when required.

I claim:

I. A hand tool for tensioning wire and the like, com- 4prising a tubular barrel, a cylinder provided with a longitudinal bore and disposed within said barrel for reciprocating movement therein, a one-way grip device in said barrel and carried by said cylinder to grip a wire passed therethrough and through said bore of said cylinder, means for reciprocating said cylinder within said barrel, movement of said cylinder in one direction serving to tension the wire held by said device and movement in the other direction permitting said device to ride freely` over said wire, and stop means normally spaced from said device and carried by said barrel, whereby displacement of said barrel together with said stop means toward said device until said stop means abuts against said device causes said device torelease said wire for removal of said tool from said wire.

2. A tool as defined in claim 1, wherein said one-way grip device includes a first member connected to said cylinder, a second member provided with wire-engaging means, and a third member connected to said second member and resilently urged away from said cylinder toward said stop means of said cylinder, the end of said third member remote from said cylinder co-operating with said stop means of said barrel in releasing said wire for removal of said tool.

3. For use in tensioning wire and the like, a hand tool which comprises a hollow first component for passing a wire axially therethrough and arranged to engage an abutment including a holding one-way grip, a second component mounted to reciprocate relative to the first component, a tensioning one-way grip device slidably carried by the second component, movement of the second component in one direction causing said tensioning device to grip and tension the wire passed through the device and movement of said second component in the other direction causing said second component to move longitudinally of said wire with the wire held stationary by said holding one-way grip, means included in said device for reciprocating said second component relative to said first component, and stop means on said first component and displaceable therewith relative to said second component to abut said tensioning one-way grip device thereagainst to disengage said tensioning one-way device from engagement with the wire.

4. A tool as defined in claim 3, wherein said means for reciprocating said second component comprises a rack and pinion.

5. A tool as defined in claim 3, wherein said tensioning one-way grip device includes a spring-loaded member provided with wire-engaging members and is displaceable relative to said second component, said stop means of said first component abutting against said spring-loaded member to displace said wire-engaging members and' 5 6 d'7. A toil :111s dened vin claim 3, further comprising an References Cited in the le of this patent a aptor w ic includes an auxiliary barrel engaging said rst component, an axially movable auxiliary member in UNITED STATES PATENTS said auxiliary barrel, said auxiliary member being resil- 833,460 HOWe Oct. 16, 1906 iently urged away from said first component, whereby 5 909,223 Reynolds Jan. 12, 1909 an auxiliary one-way grip device is provided by said 1,652,729 Rannikko Dec. 13, 1927 auxiliary barrel comprising wedges in operative engage- 1,938,601 Mason Dec. 12, 1933 ment with the resiliently urged auxiliary member of said 1,945,075 Richards et a1 Jail. 30, 1934 adaptor, said wedges being operative to grip said wire 2,080,673 Remer May 1'8, 1937 upon movement of the second component of said tool 10 2,159,633 Petersen May 23, 1939 in said other direction. 2,633,233 Berkebil Mar. 31, 1953 

